The following disclosure relates to a six-phase AC induction motor drive system. Specifically, the disclosure relates to a drive for a six-phase motor which has a single controller configuration that sends command signals to respective pulse width modulator generators associated with two three-phase power base drive sections.
FIG. 1 shows a drawing of a drive system for a six-phase AC induction motor utilizing a master and follower architecture for controlling the pulse width modulator generators associated with the drive system. The two drives are each controlled by their respective controller. Command signals are sent to each power base drive section by a respective controller. The follower controller receives command signals from the master controller, and subsequently provides command signals to its pulse width modulator generator in a shift of 30 electrical degrees in time. Although the master and follower controllers and the power base drive sections may be same model type provided by the same manufacturer, and the follower controller theoretically provides signals to its pulse width modulator generator in a precise and accurate shift of 30 electrical degrees in time relative to the master controller, slight variations in controllers and the system in general, for instance, the clocks associated with the CPUs of the controllers, nonetheless create variation which tends to destabilize and desynchronize the drive system.
The disclosure that follows provides a methodology to allow synchronizing of two three-phase power base drive sections to produce a reliable six (6) phase power system for induction loads. The disclosure herein allows for: (i) an increase in energy efficiency of an AC induction motor-drive system, (ii) a higher output power than an equivalent three-phase system operating at the same temperature and efficiency, and (iii) an extension of the life of motor winding installation for the motor of the corresponding system.